The latent, replication-competent HIV reservoir in resting CD4+ T cells is a major obstacle to curing HIV infection. All therapeutic strategies which have been developed to eliminate this latent viral reservoir rely on a targeted approach that must first reverse HIV latency. This reversal facilitates viral antigen expression, such that the infected cell can become vulnerable to immune clearance mechanisms (which may also require therapeutic or immunomodulatory enhancement strategies for greater efficacy). While recent trials demonstrated that administration of a latency reversing agents (LRAs) to HIV-infected individuals could effectively reverse viral latency in vivo, there are multiple challenges that need to be addressed before LRAs can be routinely implemented in the clinical setting. Specifically, clinically viable LRAs tested ex vivo only reverse latency in a subset of infected cells, and their maximum potency is typically much less than when cells are exposed to maximum mitogen activation. Collectively, this finding suggests that there might be limitations to the effectiveness of using a single LRA, and recent studies support the use of combinatorial LRA strategies to effectively and comprehensively purge the pool of replication-competent, integrated, latent HIV. Unfortunately, only a handful of mechanistically distinct LRAs have been identified, and consequently there is an immediate need to identify new targets for the development of potent activators of HIV-1 latency. To this end, Gilead Sciences, Inc. identified the cyanotriazole GS-46 as a new class of LRA. GS-46 strongly synergizes with proteasome inhibitors to induce HIV latency reversal at levels similar to those seen with mitogenic stimulus, but without T cell activation. The scientific premise of this R21 application is that elucidation of the mechanism(s) by which GS-46 alone, and in combination with proteasome inhibitors, reverses HIV latency will identify new targets for rational targeted development of LRAs, and will provide novel and important insights into the mechanisms responsible for the maintenance and reversal of HIV latency in resting CD4+ T cells.
The goal of this study is to elucidate of the mechanism(s) by which the cyanotriazole GS-46 reverses HIV latency in resting CD4+ T cells. This work will identify new targets for rational targeted development of latency reversing agents, and will provide unique insights into the mechanisms responsible for the maintenance and reversal of HIV latency in resting CD4+ T cells.
